Method of straightening and coating wire



June 13,1950 I J. KRAMER METHOD OF STRAIGHTENING AND COATING WIRE Filed April 11, 1946 INVENTORY Jay/v Kw/ 45e, Angl a/ Hi5 ATTORNEY.

Patented June 13, 1950 METHOD OF STRAIGHTENING AND COATING WIRE John Kramer, Waukegan, Ill., assignor to The American Steel and Wire Company of New Jersey, a corporation of New Jersey Application April 11, 1946, Serial No. 661,268

1 Claim. 1

The present invention relates to an improved method of manufacturing wire to insure that hard drawn wire will return to substantial straightness after having been coiled. While not limited thereto, the invention is well suited for use in the production of tirmed hard drawn w1re.

Practical requirements and specifications for hard drawn wire which will lie straight when uncoiled have been extremely difiicult if not impossible to meet by the methods and procedures heretofore known to those skilled in the art. The standard method of straightening the wire at the blocks does not produce satisfactory results, since the operation of straightening hard drawn wire by passing it through rolls or their equivalents effects a drop in tensile strength and develops the lowest elastic limit possible at this tensile strength level for the wire. As a result of prior practice, therefore, the wire is in its least favorable condition for rewinding on blocks without harming its straightness.

One object of my invention is to overcome the inherent deficiencies of prior practice. A further object is to provide a novel sequence of steps whereby the tensile strength and elastic limit and particularly, the elastic ratio of the wire will be increased so as to improve the condition of the wire without impairing the straightness imparted thereto by a previous straightening step.

The above and other related features of the invention will be fully apparent after consideration of the following detailed disclosure, the accompanying drawings, and the appended claims.

In the drawings:

Figure 1 is a plan view illustrating a suitable layout of apparatus for practice of the herein claimed method.

Figure 2 is an enlarged detail of the wire straightener of Figure 1.

Figure 3 is an end view illustrating means for tilting the straightener rolls.

Referring in detail to the drawings, reference numeral l designates a length of wire in the act of being drawn through a wire drawing die I2 by tension applied by a conventional form of wire drawing block H! which is adapted to be rotated by any suitable source of power, in a manner well known to those skilled in the art.

In the normal operation of the wire drawing block 14, a considerable quantity of drawn wire accumulates thereon, and the act of coiling the wire around the block imparts to the wire an inherent curvature called a cast by wire manufacturers, since it will not lie straight when unwound from the block. Under my invention I aim to overcome such inherent tendency, and I accomplish a definite benefit in straightness of the product by following the improved method hereinafter more fully described and claimed.

After a desired batch of wire has accumulated on the drawing block 14, the free end is led through a guide hole 16 in a member 18, and makes approximately a quarter turn around a guide sheave 20, thence passes through a guide hole 22 formed in a member 24. Upon emergence from the guide hole 22, the wire traverses an undulating pass defined by two sets of straightening rolls 26-26, the axis of rotation of the rolls of one set being staggered or offset with respect to that of an opposing set, as shown. After being acted upon by the straightener rolls, the wire passes through guide hole 28 formed in a member 30.

An essential and important feature of my herein claimed invention is that the wire is subjected to a heating step after the straightening operation. While not limited to such a method, the heating step can be conveniently effected by passing the wire directly from the straightener rolls through a molten bath of tin such as indicated at 32, contained in a conventional form of tin pot 34. After passing through the tin pot, the wire is wound up and accumulated on a block 36 driven by any source of power, in a manner well known and therefore not illustrated in detail. By passing the wire through the hot tin bath immediately after straightening, a beneficial change in the properties is developed which represents the maximum change in properties usually desired in tinned hard drawn wire. In order to secure straightness of an untinned wire, substantially the same method steps will be followed except that for the tin bath I substitute a heating medium such as oil or salts. I regard it as important to subject the straightened wire to a temperature of from 200 F. to 650 F., and this temperature range is readily attainable through the choice of proper heating medium. The lower temperatures will minimize the changes in tensile and torsional properties while still aiding to preserve the straightness developed by the rolls 26 which define the undulating pass. The principles of the invention are applicable to either ferrous or non-ferrous wire which has hardening characteristics in the range of 200 F. to 650 F., which will increase the elastic limit. The straightener used will preferably be so constructed that it can be tilted with respect to the axis of the wire, and for this purpose tilting screws 38 are employed which are effective to vary the angular position of the plate 40 which carries the bearing for supporting the straightener rolls 26. By this means any oficast of the wire in the coil coming from the reel M can be compensated for, and the resulting product will be found to be perfectly straight.

The novelty of my invention is based largely on a recognition of the fact that the temperature efiect following the straightening step raises the elastic limit of the product such that the straightness developed in the straightener is set, thus permitting the wire to be wound into a coil without seriously impairing the straightness previously developed. The invention also recognizes the fact that straightening operations reduce tensile strength and elastic limit and particularly the elastic ratio and that because of this it is difficult by prior practices to rewind wire on a take-up block without in part destroying the maximum straightness developed by wire straightening. By following my improved practice involving heating the wire subsequent to straightening, the quality of straightness is set or fixed by virtue of the increase in tensile strength and elastic limit and particularly the increase in the elastic limit to tensile strength ratio. The element of time in heat treatment after straightening is important, and the required measure of time can be determined by tensile and elastic limit tests in the lower portion of the temperature range specified. Practice has demonstrated, for example, that wire of 0.072" gauge, after being straightened, can satisfactorily have its straightness set by subjecting it to heat within the specified critical temperature range for a minimum period of one-half a second.

Having thus described my invention, what I wish to secure by Letters Patent is defined in the appended claim.

I claim:

In the manufacture of coiled hard-drawn tinned ferrous wire, wherein after being drawn the wire is coiled and thereby receives a curved set, a method of producing a straight set in the wire which comprises passing the wire through an undulating straightening course, heating and coating the wire immediately thereafter by passing the wire through a molten tin bath at a maximum temperature of 650 F. for a suflicient period of time for the wire to attain the bath temperature, and re-coiling the wire, the re-coiled wire having a straight set when uncoiled.

JOHN KRAMER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 182,468 Paine Sept. 19, 1876 1,522,265 Peacock Jan. 6, 1925 1,667,476 Kelley Apr. 24, 1928 2,165,368 Goss July 11, 1939 

